1. Field of the Invention
The present invention relates to a method and apparatus for filtering a multicast port identifier, and more particularly, to a method and apparatus for filtering a multicast port identifier for multicast traffic forwarding in a Gigabit-capable Passive Optical Network (GPON) system.
2. Description of the Related Art
A data forwarding scheme in a network may include a unicast forwarding scheme for “one-to-one node forward”, a broadcast forwarding scheme for “one-to-all node forward”, and a multicast forwarding scheme for a “one-to many node forwarding with respect to particular subscribers. In this instance, the multicast forwarding scheme may need a multicast protocol and a support in a corresponding network, which is different from the unicast forwarding scheme or the broadcast forwarding scheme.
A Passive Optical Network (PON) technology is one of Fiber To The Home (FTTH) technologies proposed to effectively provide a necessary bandwidth for a subscriber end. A PON is in a Point-to-Multipoint network structure where a plurality of Optical Network Units (ONUs) shares a single Optical Line Termination (OLT) using a passive element. An Optical Distribution Network (ODN) is in a tree structure where the OLT and the ONUs are connected to each other.
The PON is in the Point-to-Multipoint structure and thus may be an optimal solution for an Internet Protocol Television (IPTV) broadcasting service that needs broadcasting or multicasting.
A Gigabit-capable Passive Optical Network (GPON) standard defines only a unicast port identifier and a broadcast identifier with respect to a port identifier between an OLT and an ONT. Therefore, in order to forward a multicast packet to the ONT that is a constituent element of a multicast group, a number of packets corresponding to a number of ONTs may be copied, and a port identifier of a corresponding ONT may be attached to each of the packets.